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Jaeho Choi, Wonhee Cho, Yeon Sik Jung, Hong Suk Kang, Hee-Tak Kim
Anisotropic movement of azobenzene materials (i.e., azobenzene molecules incorporated in polymer, glass, or supramolecules) has provided significant opportunities for the fabrication of micro/nanoarchitectures. The examples include circular holes, line gaps, ellipsoidal holes, and nanofunnels. However, all of the previous studies have only focused on the lateral directional movement for the structural shaping of azobenzene materials. Herein, we propose structural shaping based on a vertical directional movement of azobenzene materials...
January 12, 2017: ACS Nano
Chengqun Qin, Yiyu Feng, Haoran An, Junkai Han, Chen Cao, Wei Feng
Multistimuli-responsive polymers are materials of emerging interest, but synthetically challenging. In this work, supramolecular assembly was employed as a facile and effective approach for constructing 3,3',5,5'-azobenzenetetracarboxylic acid (H4abtc)/poly(diallyldimethylammonium chloride) (PDAC) supramolecules. Structural transformations of H4abtc can be induced by light, mechanical force, and heat, and influenced by free volume. Thus, the fabricated freestanding H4abtc/PDAC film underwent bending/unbending movements upon treatment with light, humidity, or temperature, as asymmetric structural transformations on either side of the film generated asymmetric contraction/stretching forces...
January 12, 2017: ACS Applied Materials & Interfaces
Wei Wang, Yuan Yao, Tianchan Luo, Lingzhi Chen, Jiaping Lin, Lei Li, Shaoliang Lin
The fabrication of desired structures is one of the most urgent topics in current research on porous polymer films. Herein, the directional photo-manipulation in conjunction with breath figure processing has been demonstrated for the preparation of porous polymeric films with finely tunable pore shape and size. Because of the photo-induced directional mass migration of azobenzene units upon vertical incident linearly polarized light (LPL) irradiation, round pores on honeycomb films can be reshaped into multifarious shapes including rectangle, rhombus, dumbbell, line, etc...
January 10, 2017: ACS Applied Materials & Interfaces
Wenjun Zhan, Ting Wei, Limin Cao, Changming Hu, Yangcui Qu, Qian Yu, Hong Chen
Surfaces having dynamic control of interactions at the biological system-material interface are of great scientific and technological interest. In this work, a supramolecular platform with switchable multivalent affinity was developed to efficiently capture bacteria and on-demand release captured bacteria in response to irradiation with light of different wavelengths. The system consists of a photo-responsive self-assembled monolayer containing azobenzene (Azo) groups as guest and β-cyclodextrin (β-CD)-mannose (CD-M) conjugates as host, with each CD-M containing seven mannose units to display localized multivalent carbohydrates...
January 10, 2017: ACS Applied Materials & Interfaces
Yajun Zhang, Shuai Wang, Yanfeng Liu, Yingzhi Jin, Yijun Xia, Bo Song
The self-assembly behavior of a molecule composed of an azobenzene segment, carboxylic-acid group and flexible alkyl chains (denoted by ABA11) was studied as an extension of our proceeding work. We have previously reported that in DMSO solution ABA11 self-assembled into nanotubes starting from nanosheets and experiencing a meta-state of helical ribbons. Herein, we found that changing the solvent can also affect the self-assembly pathway of ABA11 to nanotubes. When DMSO was replaced by ethanol, the nanosheets formed by ABA11 bilayers either directly scrolled up to form nanotubes without a meta-state of helical ribbons at low concentrations, or stacked up to form nanobricks at higher concentrations...
January 9, 2017: Nanoscale
Massimo Baroncini, Giacomo Bergamini
The development of nanoscale systems capable to perform specific functions under external control is a challenging task and a fascinating objective in Chemistry. Photochromic compounds undergo radical changes in their physico-chemical properties upon light excitation, for this reason they are valuable building blocks for the construction of photo-controllable molecular devices, machines and materials. The E-Z photoisomerization of azobenzene has been known for almost 80 years and - owing to its high efficiency and excellent reversibility - has been widely employed to introduce an element of photo-control in a large variety of compounds, biomolecules, nanosystems and materials...
January 5, 2017: Chemical Record: An Official Publication of the Chemical Society of Japan ... [et Al.]
Shengyong Geng, Yuzhu Wang, Liping Wang, Tsutomu Kouyama, Toshiaki Gotoh, Satoshi Wada, Jin-Ye Wang
The structure of a self-assembly formed from a cationic azobenzene derivative, 4-cholesterocarbonyl-4'-(N,N,N-triethylamine butyloxyl bromide) azobenzene (CAB) and surfactant sodium dodecyl sulfate (SDS) in aqueous solution was studied by cryo-TEM and synchrotron radiation small-angle X-ray scattering (SAXS). Both unilamellar and multilamellar vesicles could be observed. CAB in vesicles were capable to undergo reversible trans-to-cis isomerization upon UV or visible light irradiation. The structural change upon UV light irradiation could be catched by SAXS, which demonstrated that the interlamellar spacing of the cis-multilamellar vesicles increased by 0...
January 4, 2017: Scientific Reports
Narae Shin, Kenjiro Hanaoka, Wen Piao, Takuya Miyakawa, Tomotsumi Fujisawa, Satoshi Takeuchi, Shodai Takahashi, Toru Komatsu, Tasuku Ueno, Takuya Terai, Tahei Tahara, Masaru Tanokura, Tetsuo Nagano, Yasuteru Urano
Enzyme/substrate pairs, such as β-galactosidase with chromogenic x-gal substrate, are widely used as reporters to monitor biological events, but there is still a requirement for new reporter systems, which may be orthogonal to existing systems. Here, we focused on azoreductase (AzoR). We designed and synthesized a library of azo rhodamine derivatives as candidate fluo-rogenic substrates. These derivatives were non-fluorescent, probably due to ultrafast conformational change around the N=N bond after photoexcitation...
December 30, 2016: ACS Chemical Biology
Ken-Ichi Yuyama, Lionel Marcélis, Pei-Mei Su, Wen-Sheng Chung, Hiroshi Masuhara
Laser trapping in chemistry covers various studies from single molecules, nanoparticles, and quantum dots to crystallization and liquid-liquid phase separation of amino acids. In this work, a supramolecular assembly of azobenzene-based biscalix[4]arene is generated in ethyl acetate by laser trapping; its nucleation and growth are elucidated. No trapping behavior was observed when a 1064 nm laser beam was focused inside the solution; however, interesting assembling phenomena were induced when it was shined at the air/solution interface...
December 29, 2016: Langmuir: the ACS Journal of Surfaces and Colloids
Seong Ho Ryu, Min-Jun Gim, Wonsuk Lee, Suk-Won Choi, Dong Ki Yoon
Photonic crystals (PCs) have recently attracted considerable attention, with much effort devoted to photonic bandgap (PBG) control for varying the reflected color. Here, fabrication of a modulated one-dimensional (1D) anodic aluminum oxide (AAO) PC with a periodic porous structure is reported. The PBG of the fabricated PC can be reversibly changed by switching the ultraviolet (UV) light on/off. The AAO nanopores contain a mixture of photoresponsive liquid crystals (LCs) with irradiation-activated cis/trans photoisomerizable azobenzene...
January 10, 2017: ACS Applied Materials & Interfaces
Madeleine K Adam, Yingxue Hu, Jessica S Poisson, Matthew J Pottage, Robert N Ben, Brendan L Wilkinson
Cryopreservation is an important technique employed for the storage and preservation of biological tissues and cells. The limited effectiveness and significant toxicity of conventionally-used cryoprotectants, such as DMSO, have prompted efforts toward the rational design of less toxic alternatives, including carbohydrate-based surfactants. In this paper, we report the modular synthesis and ice recrystallization inhibition (IRI) activity of a library of variably substituted, carbohydrate-based fluorosurfactants...
December 14, 2016: Carbohydrate Research
Joaquín Calbo, Claire E Weston, Andrew White, Henry Rzepa, Julia Contreras-García, Matthew J Fuchter
Photoswitchable compounds, which can be reversibly switched between two isomers by light, continue to attract significant attention for a wide array of applications. Azoheteroarenes represent a relatively new but understudied type of photoswitch, where one of the aryl rings from the conventional azobenzene class has been replaced with a five-membered heteroaromatic ring. Initial studies have suggested the azoheteroarenes - the arylazopyrazoles in particular - to have excellent photoswitching properties (quantitative switching and long Z isomer half-life)...
December 23, 2016: Journal of the American Chemical Society
Yuyun Liu, Bo Xu, Shengtong Sun, Jia Wei, Limin Wu, Yanlei Yu
Azobenzene-containing cross-linked liquid crystal polymer films without hydrophilic groups exhibit dual-responsivity to humidity and UV light. The films realize not only a series of large and sophisticated contactless motions by utilizing moisture, including an inchworm walk, and tumbling locomotion, but also dual-mode actuation that can be applied in flexible electronics.
December 23, 2016: Advanced Materials
Kizhisseri Devi Renuka, C Lalitha Lekshmi, Kuruvilla Joseph, Sankarapillai Mahesh
Tuning the microstructure, conductance, band gap of a single molecule with an external stimuli such as light have vital importance in nanoscale molecular electronics. Azobenzene systems are inimitable light responsive molecules suitable for the development of optically modulated materials. In this work we have demonstrated the development of an optically active Multiwalled Carbon Nanotube (MWCNT)-hybrid material by the noncovalent functionalization of azo based chromophore derived from cardanol, a bioresource material...
January 18, 2017: ACS Applied Materials & Interfaces
Cong Bin Fan, Zhi Qiang Liu, Le Le Gong, An Min Zheng, Le Zhang, Chang Sheng Yan, Hui Qiong Wu, Xue Feng Feng, Feng Luo
The first MOF (metal-organic framework) built on both diarylethene and azobenzene photochromic units is reported here and displays distinct photoresponses for different guest molecules, thus creating an easy-to-use pathway to modulate the adsorption selectivity of MOF materials.
December 21, 2016: Chemical Communications: Chem Comm
Janin T Offenloch, Johannes Willenbacher, Pavleta Tzvetkova, Carolin Heiler, Hatice Mutlu, Christopher Barner-Kowollik
We introduce the facile synthesis of fluorescent single-chain nanoparticles (SCNPs) based on chain-shattering acyclic diene metathesis (ADMET) polymers featuring self-immolative azobenzene motifs. An electrophilic alkoxyetherification is utilized to introduce the photoreactive moieties required for the subsequent chain collapse via UV-induced nitrile imine-mediated tetrazole-ene cycloaddition (NITEC).
December 21, 2016: Chemical Communications: Chem Comm
Kyohhei Fujita, Shoji Fujiwara, Tatsuru Yamada, Yuji Tsuchido, Takeshi Hashimoto, Takashi Hayashita
In this study, we have developed a rational design strategy to obtain highly selective supramolecular recognition systems of cyclodextrins (CyDs) on the basis of the lock and key principle. We designed and synthesized dipicolylamine (dpa)-modified γ-CyD-Cu(2+) complexes possessing an azobenzene unit (Cu·1-γ-CyD) and examined how they recognized phosphoric acid derivatives in water. The results revealed that Cu·1-γ-CyD recognized ATP with high selectivity over other phosphoric acid derivatives. The significant blue shift in the UV-vis spectra and (1)H NMR analysis suggested that the selective ATP recognition was based on the multipoint interactions between the adenine moiety of ATP and both the CyD cavity and the azobenzene unit in addition to the recognition of phosphoric moieties by the Cu-dpa complex site...
January 5, 2017: Journal of Organic Chemistry
Alexis Goulet-Hanssens, Manuel Utecht, Dragos Mutruc, Evgenii Titov, Jutta Schwarz, Lutz Grubert, David Bléger, Peter Saalfrank, Stefan Hecht
A variety of azobenzenes were synthesized to study the behavior of their E and Z isomers upon electrochemical reduction. Our results show that the radical anion of the Z isomer is able to rapidly isomerize to the corresponding E configured counterpart with a dramatically enhanced rate as compared to the neutral species. Due to a subsequent electron transfer from the formed E radical anion to the neutral Z starting material the overall transformation is catalytic in electrons; i.e., a substoichiometric amount of reduced species can isomerize the entire mixture...
December 20, 2016: Journal of the American Chemical Society
Zhengbang Wang, Alexander Knebel, Sylvain Grosjean, Danny Wagner, Stefan Bräse, Christof Wöll, Jürgen Caro, Lars Heinke
Metal-organic frameworks offer tremendous potential for efficient separation of molecular mixtures. Different pore sizes and suitable functionalizations of the framework allow for an adjustment of the static selectivity. Here we report membranes which offer dynamic control of the selectivity by remote signals, thus enabling a continuous adjustment of the permeate flux. This is realized by assembling linkers containing photoresponsive azobenzene-side-groups into monolithic, crystalline membranes of metal-organic frameworks...
December 20, 2016: Nature Communications
Caterina Cocchi, Thomas Moldt, Cornelius Gahl, Martin Weinelt, Claudia Draxl
In a joint theoretical and experimental work, the optical properties of azobenzene-functionalized self-assembled monolayers (SAMs) are studied at different molecular packing densities. Our results, based on density-functional and many-body perturbation theory, as well as on differential reflectance (DR) spectroscopy, shed light on the microscopic mechanisms ruling photo-absorption in these systems. While the optical excitations are intrinsically excitonic in nature, regardless of the molecular concentration, in densely packed SAMs intermolecular coupling and local-field effects are responsible for a sizable weakening of the exciton binding strength...
December 21, 2016: Journal of Chemical Physics
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